Device for lowering a dump truck bed

ABSTRACT

A device and method for automatically lowering the bed of a dump truck by disengaging the hydraulic pump and the power take-off when the dump vehicle reaches or exceeds a predetermined speed or when the transmission is shifted to or above a predetermined gear. A conventional dump truck speedometer or transmission system is utilized.

TECHNICAL FIELD

This invention relates to a device and method for lowering a dump truckbed. More particularly, this invention relates to a device and methodfor automatically lowering the bed of a dump truck upon attaining apredetermined speed or gear in operation of the dump truck.

BACKGROUND OF THE INVENTION

In a conventional dump truck, material such as dirt, sand or gravel istransported from one location to another and then "dumped" on theground. The material is dumped by elevating one end of the dump bed suchthat the material slides out the other end. The dump bed is elevated bymeans of a hoist operated by a hydraulic pump. The hydraulic pump ispowered by engine power diverted to the pump by means of a powertake-off ("PTO"). The PTO is a supplementary mechanism that enablesengine power to be used for auxiliary systems on the dump truck, such asthe hydraulic pump.

In order to raise the dump bed, the dump truck driver or operatorengages the PTO, which diverts engine power to the hydraulic pump. Thedriver then engages the hydraulic pump which operates the hoist andlifts the dump truck bed. The PTO and the hydraulic pump are engaged bymeans of a controller generally located in the cab of the truck.

In normal operation, once the dump truck driver has dumped the materialat a job site, he is to lower the bed with the hydraulic pump anddisengage the PTO before traveling down the highway. It is not uncommon,however, for a driver to leave inadvertently the bed raised or the PTOengaged. In the worst case scenario, the height of the truck with thebed raised may exceed the height of a bridge or other overhead object.Should a dump truck traveling with the bed in the raised position strikea bridge, the damage to the truck, driver and bridge can be significant.Similarly, if the PTO is left engaged it can easily overheat, causingdamage to the truck and, on occasion, injury to the driver orbystanders.

Currently known devices disclosed in the literature to disengageautomatically the hydraulic pump and the PTO are not adequate for normaldump truck operation. For example, Japanese Patent No. 60-151139 toToukiyuu Shiyariyou Seizou K.K. discloses a dump truck operation warningdevice. The PTO is automatically cut off and a warning device isactivated after the hydraulic pump has been operated for a certainamount of time while traveling with the PTO engaged.

The disadvantage of this system is that it limits the ability of thedump truck operator to perform certain low speed operations with the bedraised. These operations would include, for example, gravel spreading. Asystem that is time controlled, i.e., based on the amount of time thehydraulic pump has been operated or the PTO has been engaged, isincompatible with low-speed gravel spreading because it would interruptthe job by automatically lowering the dump bed.

Despite the various efforts found in the prior art, there remains a needfor a speed or a gear controlled dump truck system in order to increasesafety while at the same time permit low speed operations. Such a systemwould ensure that the dump truck could not obtain high speed or highgear with the bed raised while maintaining the versatility needed forjob site operations.

SUMMARY OF THE INVENTION

The present invention fills the need in the prior art by providing adevice and method that automatically disengages the hydraulic pump andthe PTO, thereby lowering the dump truck bed, when the truck reaches orexceeds a predetermined speed or gear. The invention permits low speedor low gear operation of the truck with the bed raised to permit gravelspreading or other low speed job site operations. Once the truck exceedsthe predetermined speed or gear, the bed is lowered automatically andthe manual control means of the hydraulic pump and the PTO cannot bereengaged until the vehicle slows or gears down.

In a preferred embodiment, the invention comprises a mechanical valve,such as a flyweight valve or other type of governor, connected to thespeedometer of a dump truck. In this embodiment, the speedometer wouldoperate mechanically.

The mechanical valve controls an air line running from any air tank onthe truck, such as that used to operate the pneumatic brakes, to the"control device" located in the cab of the truck. The control devicecontains the manual control means of the hydraulic pump and the PTO.

The purpose of the invention is to automatically operate these manualcontrol means. This is accomplished within the control device by aircylinders attached to the incoming air lines that force the manualcontrol means to disengage when the mechanical valve is triggered andopens the air lines. When the vehicle reaches or exceeds thepredetermined speed as measured by the speedometer, the mechanical valveopens the air lines allowing air from the air tank through the air linesinto the air cylinders within the control device. The air cylinders, ina piston-like action, then operate lever and wheel assemblies such thatthe manual control means for the hydraulic pump and the PTO aredisengaged, thereby lowering the dump truck bed. The valve remains openuntil the truck slows below the predetermined speed, thereby preventingthe manual control means of the hydraulic pump and the PTO from beingreengaged.

The present invention further includes utilizing the transmission systemof a dump truck. For example, in trucks containing a Fuller-brandtransmission, characterized by pneumatically assisted shifting, an airline can be run from the air range shifter valve in the transmissionsystem directly to the "control device" in the cab of the truck. Oncethe transmission is shifted to the predetermined gear, air is releasedfrom the air range shifter valve through the air line into the aircylinders within the control device. The invention then operates asdescribed above. Likewise, the manual control means of the hydraulicpump and the PTO cannot be reengaged until the truck is geared downbelow the predetermined gear.

Other embodiments would include the use of an electric solenoid switchrather than a mechanical valve. The electric solenoid switch wouldoperate in conjunction with an electric speedometer. The invention wouldthen operate as disclosed above.

Further, other possible embodiments would include an all electric systemwhereby electric motors would replace the air cylinders within thecontrol box. Likewise, any type of motion sensor may be employed as aspeed control device. In sum, the invention may operate using mechanizeddevices, electrical devices, or any combination thereof.

Thus, it is an object of the present invention to provide a device andmethod for lowering automatically a dump truck bed.

It is a further object to provide a dump truck safety system thatautomatically lowers the dump truck bed when the truck reaches apredetermined speed or gear.

It is a further object of the present invention to provide a device andmethod by which the hydraulic pump and the power take off of a dumptruck are automatically disengaged when the truck reaches apredetermined speed or gear.

A still further object of the present invention is to prevent theengagement of the hydraulic pump or the power take off of a dump truckuntil the truck is below a predetermined speed or gear.

Other objects, features, and advantages of the present invention willbecome apparent upon reading the following specification, when taken inconjunction with the drawings and the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view showing the positioning of the pertinentelements of the invention within a typical dump truck shown in phantomlines.

FIG. 2 is a perspective view showing the positioning of the pertinentelements within control device, shown in phantom lines, with theremainder of the invention organized in block form.

FIG. 3 is a block diagram showing an alternative gear-based embodimentof the invention.

FIG. 4 is a block diagram showing an electrical alternative embodimentof the invention.

DETAILED DESCRIPTION

FIG. 1 is a perspective view showing the positioning of the pertinentelements of the invention within a typical dump truck shown in phantomlines. As can be seen, control device 1 is located in cab 21 of dumptruck 20. Dump bed 24 is raised and lowered by hoist 23 which is poweredby hydraulic pump 10. The power from engine 22 is transmitted tohydraulic pump 10 via power take-off (PTO) 11. When the manual controlmeans 7 of PTO 11 and manual control means 6 of hydraulic pump 10 areengaged, PTO 11 diverts power from engine 22 to hydraulic pump 10, whichoperates hoist 23, thereby elevating dump bed 24.

A mechanical valve 13 is functionally connected to speedometer 14 whichmeasures the speed of dump truck 20. The mechanical valve 13 isgenerally a flyweight valve or other governor-type device. Mechanicalvalve 13 operates an air line running from air tank 12 to controldevice 1. Air tank 12 can be any air supply on dump truck 20, such asthat used to operate the pneumatic brakes. In this embodiment,speedometer 14 is mechanical, but as explained below, an electricalspeedometer may also be employed in the invention.

The control device 1 itself consists of two air cylinders 2 and 3 (notshown in FIG. 1) connected to the incoming air lines (a). Air cylinders2 and 3 act in a piston-like manner when air is forced in through airlines (a). The air cylinders 2 and 3 operate lever and wheel assemblies4 and 5 (not shown in FIG. 1) which are attached to the manual controlmeans 6 of the hydraulic pump 10 and the manual control means 7 of thePTO 11.

In normal operation, when the speed of dump truck 20, as measured byspeedometer 14, reaches or exceeds a predetermined speed, mechanicalvalve 13 opens air lines (a), allowing air from air tank 12 through airlines (a) into air cylinders 2 and 3 located within control device 1.For example, the predetermined speed may be 15 to 20 miles per hour. Aircylinders 2 and 3 then operate lever and wheel assemblies 4 and 5 suchthat manual control means 6 and 7 of hydraulic pump 10 and PTO 11respectively, are forced to disengage. Once the manual control means 6and 7 are disengaged, PTO 11 stops transmitting power to hydraulic pump10 and hydraulic pump 10 loses pressure such that hoist 21 lowers dumpbed 24.

Mechanical valve 13 will remain open until the speed of dump truck 20,as measured by speedometer 14, is reduced below the predetermined speed.Until the speed of dump truck 20 is so reduced, the manual control means6 of the hydraulic pump 10 and the manual control means 7 of the PTO 11cannot be reengaged.

FIG. 2 is a perspective view showing the positioning of the pertinentelements within control device 1, shown in phantom lines, with theremainder of the invention organized in block form. As described above,control device 1 contains the manual control means 6 and 7 of hydraulicpump 10 and PTO 11, respectively The manual control means 6 and 7operate the hydraulic pump 10 and the PTO 11 via cables (b). Likewise asdescribed above, control device 1 is connected to mechanical valve 13via two air lines (a). Each air line (a) is connected to a correspondingair cylinder 2 and 3. The air cylinders 2 and 3 are of normalconstruction and act as a piston when air lines (a) open. Air cylinders2 and 3 are functionally connected to a corresponding one of lever andwheel assemblies 4 and 5. Lever and wheel assemblies 4 and 5 areconnected to manual control means 6 and 7 of hydraulic pump 10 and PTO16. In normal operation, when mechanical valve 13 opens, air from airtank 12 flows through air lines (a) into air cylinders 2 and 3. Aircylinders 2 and 3 fill with air and force lever and wheel assemblies 4and 5 to disengage manual control means 6 and 7. Once manual controlmeans 6 and 7 are disengaged, PTO 11 stops transmitting power tohydraulic pump 10 and hydraulic pump 10 loses pressure such that hoist21 is lowered, thereby lowering the dump bed.

In order to install the invention, air lines (a) are run from the airtank 12 to the control device 1. Mechanical valve 13 is inserted in theair lines (a) and functionally connected to the speedometer 14. Cables(b) are then run from the manual control means 6 and 7 of hydraulic pump10 and PTO 11 contained within control device 1 to the hydraulic pump 10and PTO 11.

FIG. 3 is a block diagram showing an alterative gear based embodiment ofthe invention. In trucks employing a Fuller-brand transmission system orthe like, the invention may operate based upon a predeterminedtransmission gear rather than truck speed. Truck transmission 40selectively operates the powered wheel drive of truck 20 in reverse,neutral and various forward gears by manual gear shifter 43. Thetransmission 40 is air-assisted such that air from air tank 12 isemployed via the air range shifter valve 42 attached to gear shifter 43.Air lines (c) are run from the air range shifter valve 42 via a "T"connection 44 to control device 1.

In normal operation, when gear shifter 43 shifts transmission 40 to orabove a predetermined gear, air range shifter valve 42 releases air fromair tank 12 into air lines (c) such that the invention is operated asdescribed above. For example, the predetermined gear may be fourth orfifth gear. Likewise, the manual control means and hydraulic pump 10 andPTO 11 cannot be reengaged until the truck is geared down below thepredetermined gear.

FIG. 4 is a block diagram showing an electrical alternative embodimentof the invention. Rather than mechanical speedometer 14 disclosed above,an electric speedometer 30 may be employed. The electric speedometer 30is connected to an electric solenoid switch 33 rather than themechanical valve 13. The electric solenoid switch 33 is inserted intoair lines (a). In normal operation, when dump truck 20 as measured byspeedometer 30, reaches or exceeds a predetermined speed, the electricsolenoid switch 33 is opened, thereby allowing the invention to operateas described above.

It can be appreciated that the electric solenoid switch 33 also may betriggered at a predetermined gear of the transmission 40 (not shown) orby control means other than speedometer 30 or 13. Similarly, in analternative to the use of said air tank 12, air lines (a) or (c) and aircylinders 2 and 3, a fully electric setup (not shown) may be employed.Air cylinders 2 and 3 may be replaced within control device 1 withelectric motors connected to the electric solenoid switch 33. Similarly,air tank 12 and air lines (a) or (c) are replaced with the use of abattery and an electric circuit. When the truck reaches or exceeds apredetermined speed or gear, the electric solenoid switch 33 energizesan electric circuit that causes the electric motors to operate asdescribed above. Further, the electrical setup can be simplified byoperating an electric governor directly off transmission 40 such that agovernor-activated line powers the electric motors within the controldevice as described above.

It is to be understood that this description is not meant to be limitingbecause further modifications may now suggest themselves to thoseskilled in the art and is intended to cover such modifications as fallwithin the scope of the following claims.

I claim:
 1. An improved dump truck vehicle, comprising:a dump vehicleincluding a dump bed whereby material is carried in and dumped from saiddump bed; means for measuring the speed of said dump vehicle; and meansresponsive to said speed measuring means for automatically lowering saiddump bed when said dump vehicle attains a predetermined speed; saidpredetermined speed capable of being set.
 2. The improved dump vehicleof claim 1 wherein said means for automatically lowering said dump bedfurther comprises means for controlling said dump bed.
 3. The improveddump vehicle of claim 2 wherein said means for controlling said dump bedcomprises:a hydraulic pump to raise and lower said dump bed, includingmanual control means for selectively operating said hydraulic pump; anda power take-off to power said hydraulic pump, including manual controlmeans for selectively operating said power take-off.
 4. The improveddump vehicle of claim 3 wherein said means for measuring the speed ofsaid dump vehicle consists of a mechanical speedometer.
 5. The improveddump vehicle of claim 4 wherein said means for controlling saidoperating means for said dump bed comprises a flyweight valve operatingin conjunction with said mechanical speedometer;said flyweight valveoperating the opening and closing of an air line at said predeterminedspeed of said dump vehicle as measured by said mechanical speedometer;said air line connected at one end to an air tank and connected to aircylinders at the other end; said air cylinders connected operably tolever and wheel assemblies; said lever and wheel assemblies connected tosaid manual control means of said hydraulic pump and said manual controlmeans of said power take-off, such that when the speed of said dumpvehicle as measured by said mechanical speedometer reaches or exceedssaid predetermined speed, said fly-weight valve opens said air line,releasing air from said air tanks through said air lines into said aircylinders, said air cylinders operating said lever and wheel assembliessuch that said manual control means of said hydraulic pump and saidmanual control means of said power take-off are disengaged, therebylowering said dump bed.
 6. The improved dump vehicle of claim 4 whereinsaid means responsive to said speed measuring means for automaticallylowering said dump bed prevent the operation of said hydraulic pumpmanual control means and the operation of said power take-off manualcontrol means once the speed of said dump vehicle as measured by saidmechanical speedometer is greater than said predetermined speed untilthe speed of said dump vehicle as measured by said mechanicalspeedometer is less than said predetermined speed as measured by saidmechanical speedometer.
 7. The improved dump vehicle of claim 4 whereinsaid predetermined velocity is 15 to 20 miles per hour.
 8. The improveddump vehicle of claim 3 wherein said means for measuring the speed ofsaid dump vehicle is an electrical speedometer.
 9. The improved dumpvehicle of claim 8 wherein said means for controlling said operatingmeans for said dump bed comprises an electric solenoid switch operatingin conjunction with said electrical speedometer;said electric solenoidswitch operating the opening and closing of an air line at saidpredetermined speed of said dump vehicle as measured by said electricalspeedometer; said air line connected at one end to an air tank andconnected to air cylinders at the other end; said air cylindersconnected operably to lever and wheel assemblies; said lever and wheelassemblies connected to said manual control means of said hydraulic pumpand said manual control means of said power take-off such that when thespeed of said dump vehicle as measured by said electrical speedometerreaches or exceeds said predetermined velocity, said electric solenoidswitch opens said air line, releasing air from said air tank throughsaid air line into said air cylinders, said air cylinders operating saidlever and wheel assemblies such that said manual control means of saidhydraulic pump and said manual control means of said power take-off aredisengaged, thereby lowering said dump bed.
 10. The improved dumpvehicle of claim 8 wherein said means for controlling said operatingmeans for said dump bed consists of an electric solenoid switch;saidelectric solenoid switch operating the energizing of an electric circuitat said predetermined speed of said dump vehicle as measured by saidelectric speedometer; said electric circuit connected to a battery andto electric motors; said electric motors connected operably to lever andwheel assemblies; said lever and wheel assemblies connected to saidmanual control means of said hydraulic pump and to said manual controlmeans of said power take-off, such that when the speed of said dumpvehicle as measured by said electrical speedometer reaches or exceedssaid predetermined speed, said electric solenoid switch said electriccircuit, causing said electric solenoids and motors to operate saidlever and wheel assemblies such that said manual control means of saidhydraulic pump and said manual control means of said power take-off aredisengaged, thereby lowering said dump bed.
 11. The improved dumpvehicle of claim 8 wherein said means responsive to said speed measuringmeans for automatically lowering said dump bed prevent the operation ofsaid hydraulic pump manual control means and manual operation of saidpower take-off manual control means once the speed of said dump vehicleas measured by said electrical speedometer is greater than saidpredetermined speed until the speed of said dump vehicle as measured bysaid electrical speedometer is less than said predetermined speed asmeasured by said electrical speedometer.
 12. The improved dump vehicleof claim 8 wherein said predetermined velocity is 15 to 20 miles perhour.